Abstract

Consumption of some dietary fibres may benefit bowel health; however, the effect of Australian sweet lupin (Lupinus angustifolius) kernel fibre (LKFibre) is unknown. The present study examined the effect of a high-fibre diet containing LKFibre on bowel function and faecal putative risk factors for colon cancer compared to a control diet without LKFibre. Thirty-eight free-living, healthy men consumed an LKFibre and a control diet for 1 month each in a single-blind, randomized, crossover study. Depending on subject energy intake, the LKFibre diet was designed to provide 17-30 g/d fibre (in experimental foods) above that of the control diet. Bowel function self-perception, frequency of defecation, transit time, faecal output, pH and moisture, faecal levels of SCFA and ammonia, and faecal bacterial beta-glucuronidase activity were assessed. In comparison to the control diet, the LKFibre diet increased frequency of defecation by 0.13 events/d (P=0.047), increased faecal output by 21 % (P=0.020) and increased faecal moisture content by 1.6 % units (P=0.027), whilst decreasing transit time by 17 % (P=0.012) and decreasing faecal pH by 0.26 units (P<0.001). Faecal butyrate concentration was increased by 16 % (P=0.006), butyrate output was increased by 40 % (P=0.002) and beta-glucuronidase activity was lowered by 1.4 micromol/h per g wet faeces compared to the control diet (P<0.001). Addition of LKFibre to the diet incorporated into food products improved some markers of healthy bowel function and colon cancer risk in men.